Tapping method and device, and punch press

ABSTRACT

A tapping method includes engaging a front end of a tap with a prepared hole formed in a workpiece. The tap is provided at a tapping tool attached to a rotating mold indexing device that includes a control motor M. The rotating mold indexing device is rotatably provided at a punch press. The tapping method also includes rotating the control motor M positively to rotate the tap positively when the front end of the tap is engaged with the prepared hole. The tapping method also includes stopping positive rotation of the control motor M and rotating the motor reversely, thereby to detach the tap from the prepared hole of the workpiece, when it is detected that the control motor M has rotated a determined number of times or that a predetermined time has elapsed.

TECHNICAL FIELD

The present invention relates to a tapping method of performing tappingprocess to a prepared hole formed in a plate-like work by a punch presssuch as a turret punch press, a tapping device and the punch press, morespecifically, a method of performing tapping process by using a rotatingmold indexing device provided in the punch press and a tapping deviceand a punch press capable of determining whether or not the tap isbroken.

BACKGROUND ART

Conventionally, in a punch press such as a turret punch press, atechnique of performing burring process or drilling process to aplate-like work and then performing tapping process to the partsubjected to burring process or a prepared hole has been disclosed. Thetechnique is disclosed in, for example, Japanese Patent ApplicationLaid-Open No. 8-71848 (hereinafter referred to as “patent document 1”)and Japanese Patent Application Laid-Open No. 9-155638 (hereinafterreferred to as “patent document 2”).

Further, the configuration in which tapping process is performed byattaching a tapping device to a rotating mold indexing device rotatablyprovided at the punch press has been developed. It is disclosed in, forexample, Japanese Utility Model Registration Publication No. 2541404(hereinafter referred to as “patent document 3”) and Japanese PatentApplication Laid-Open No. 7-185975 (hereinafter referred to as “patentdocument 4”).

On the other hand, in a conventional tapping device, as a configurationof detecting whether or not a tap is broken, the configuration in whichan operator activated by the tap passing through a work is provided at atap die supporting the work in opposed to the tap and breakage of thetap is detected by detecting that this operator has been activated by asensor such as a micro switch has been developed. It is disclosed in,for example, Japanese Patent Application Laid-Open No. 9-47197(hereinafter referred to as “patent document 5”).

According the invention described in the patent document 1, it is theconfiguration in which linear motion when a head member in a rotationaltool device with a rotational tool such as tap and reamer is pressed andlowered by a vertically-movable ram (striker) provided at the punchpress is converted into rotational motion, thereby to rotate therotational tool.

The above-mentioned configuration has the following problems: conversionof linear motion into rotational motion makes the configurationcomplicated and a short length of vertical stroke of the ram requiresincreasing the number of the rotational tool, resulting in shortlifetime of the tap.

According the invention described in the patent document 2, since aprocess position by the punch press greatly deviates from a tappingprocess position by the tapping device, when a prepared hole isprocessed in the vicinity of the end part of the work for tappingprocess, a work holding position by a work positioning device forpositioning transfer position of the work needs to be changed and amotor for driving the tapping device or the like needs to be providedseparately.

Accordingly, to improve processing efficiency and simplify theconfiguration, further improvement is desired.

According the invention described in the patent document 3, since thetapping tool is attached to the rotating mold indexing device providedat the punch press and the tapping tool is rotated by using the motor ofthe rotating mold indexing device, the above-mentioned problems in thecited references 1 and 2 can be solved. However, in this configuration,the tap is fed by providing a master screw and rotating speed of the tapis increased by using a planetary gear drive or the like, leading to theproblem that the whole configuration becomes complicated.

According the invention described in the patent document 4, since thetapping tool is attached to the rotating mold indexing device providedat the punch press and the tap is rotated by using the motor of therotating mold indexing device to perform tapping process, a head parthas an engaging part with the ram and a speed increasing mechanism forincreasing the rotational speed of the tap in the state where the ram isengaged with the engaging part is provided, resulting in morecomplicated configuration.

Further, in the patent document 5, by turning ON or OFF the micro switchas a sensor by operation of the operator provided at the tap die,breakage of the tap is detected and when the micro switch breaks down inthe ON or OFF state, it is difficult to determine whether the ON or OFFstate is caused by failure of the breakage of the tap or the microswitch.

In the patent document 5, there is a problem that the operator providedat the tap die is an obstacle when discharging chips generated duringtapping process.

To solve the above-mentioned problems, a first object of the presentinvention is to provide a tapping method, a tapping device and a punchpress which can readily perform tapping process by using the rotatingmold indexing device provided at the punch press with simpleconfiguration.

A second object of the present invention is to provide a tapping method,a tapping device and a punch press which can detect breakage of the tapand failure of the sensor for detecting the breakage.

Further, a third object of the present invention is to provide a tappingmethod, a tapping device and a punch press which can suck and dischargechips generated during tapping process.

DISCLOSURE OF THE INVENTION

In order to achieve the above objects, a tapping method for performingtapping process in a punch press according to a first aspect of thepresent invention comprises steps of: (a) engaging a front end of a tapprovided at a tapping tool attached to a rotating mold indexing devicerotatably provided at the punch press with a prepared hole formed in awork; (b) when the front end of the tap is engaged with the preparedhole, rotating a control motor of the rotating mold indexing devicepositively to rotate the tap positively; and (c) when it is detectedthat the control motor of the rotating mold indexing device has rotateda determined number of times, stopping positive rotation of the controlmotor and rotating the motor reversely, thereby to detach the tap fromthe prepared hole of the work.

A tapping method for performing tapping process in a punch pressaccording to a second aspect of the present invention comprises stepsof: (a) engaging a front end of a tap provided at a tapping toolattached to a rotating mold indexing device rotatably provided at thepunch press with a prepared hole formed in a work; (b) when the frontend of the tap is engaged with the prepared hole, rotating a controlmotor of the rotating mold indexing device positively to rotate the tappositively; and (c) when it is detected that predetermined time haselapsed since the control motor of the rotating mold indexing devicestarted rotating, stopping positive rotation of the control motor androtating the motor reversely, thereby to detach the tap from theprepared hole of the work.

A tapping device according to a third aspect of the invention comprises:a tap holder provided in a shank body which can be freely attached to arotating mold indexing device rotatably provided at a punch press so asto be movable in the vertical direction, the tap holder having a tap atits lower end and being provided so as to be movable only in thevertical direction and urged upwards; and a downward movementtransmitting means for transmitting downward motion of a ram provided atthe punch press so as to be movable in the vertical direction to the tapholder, the downward movement transmitting means being at an upper partof the shank body.

A tapping device according to a fourth aspect of the inventioncomprises: a tap holder provided in a shank body which can be freelyattached to a rotating mold indexing device rotatably provided at apunch press so as to be movable in the vertical direction, the tapholder having a tap at its lower end and being provided so as to bemovable only in the vertical direction and urged upwards; and a downwardmovement transmitting means for transmitting downward motion of a ramprovided at the punch press so as to be movable in the verticaldirection to the tap holder; wherein the downward movement transmittingmeans has a pressing means for pressing the tap holder downwards byfluid pressure supplied from the ram and a shock absorbing means.

A tapping device according to a fifth aspect of the invention, is atapping device as stated in the third or the fourth aspect, wherein awork brace is rotatably provided at a lower end of the shank body.

A tapping device according to a sixth aspect of the invention, is atapping device as stated in the third, the fourth or the fifth aspect,wherein an oil channel for guiding oil supplied from the ram to the tapis provided in the downward movement transmitting means and the tapholder.

A tapping device according to a seventh aspect of the invention, is atapping device as stated in the third, the fourth, the fifth or thesixth aspect, wherein an elastic member which can freely transmitdownward motion of the ram is provided at the downward movementtransmitting means to lower the tap holder against upward energizingforce of the tap holder.

A punch press according to a eighth aspect of the invention, is a punchpress with a rotating mold indexing device for performing rotationindexing of a rotating mold comprising: a control motor for drivingrotation of the rotating mold indexing device; and a motor control meanswhich can freely control the control motor in response to rotationindexing of the rotating mold and tapping process by a tapping toolattached to rotating mold indexing device.

A punch press according to a ninth aspect of the invention is a punchpress as stated in the eighth aspect, wherein the motor control meanshas a rotation direction switch means for stopping positive rotation ofthe control motor and switching to reverse rotation when it is detectedthat the control motor has rotated a predetermined number of times orthat predetermined time has elapsed since start of positive rotation.

A tapping device according to a tenth aspect of the invention comprises:a tap die for supporting a work as opposed to a tap for performingtapping process with respect to a prepared hole formed in the work; anoperator which is provided at the tap die and activated by the tappassing through the work; a sensor for detecting that the operator hasbeen activated; and a sensor monitoring means for monitoring the stateof the sensor.

A tapping device according to a eleventh aspect of the inventioncomprises: a tap die for supporting a work as opposed to a tap forperforming tapping process with respect to a prepared hole formed in thework; an operator which is provided at the tap die and activated by thetap passing through the work; and an air exhaust hole for ejecting airinto a discharge hole in the operator at activation of the operator.

A tapping device according to a twelfth aspect of the invention is atapping device as stated in the eleventh aspect, wherein the air exhausthole is directed to the discharging direction of the discharge hole.

As understood from the description described above, according to thepresent invention, tapping processing can be easily performed withsimple configuration by using the motor of the rotating mold indexingdevice provided at the punch press and therefore, the above-mentionedconventional problems can be solved.

Further, according to the present invention, it is possible to detectfailure of the sensor for detecting breakage of the tap as well asbreakage of the tap and suck and discharge chips generated duringtapping process, and therefore, the above-mentioned conventionalproblems can be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view illustrating functions of a punch press and atapping tool in accordance with an embodiment of the present invention.

FIG. 2 is a sectional view of a partially-improved configuration of thetapping tool in accordance with an embodiment of the present invention.

FIG. 3 is an explanatory view showing a tapping processing device inaccordance with an embodiment of the present invention schematically andconceptually.

FIG. 4 is a block diagram showing a configuration of a main part in acontrol device of the tapping processing device.

FIG. 5 is a flow chart showing an operation of detecting breakage of atap.

FIG. 6 is a flow chart showing an operation of detecting breakage of thetap.

FIG. 7 is a sectional view of the tapping processing device fordetecting breakage of the tap.

FIG. 8 is a sectional view of the tapping processing device fordetecting breakage of the tap.

FIG. 9 is a plan view of the tapping processing device for detectingbreakage of the tap.

FIG. 10 is a sagittal sectional view taken along X-X in FIG. 8.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of a tapping method, a tapping device and a punch press ofthe present invention will be described in detail with reference tofigures.

Referring to FIG. 1, the punch press of this embodiment has an upperholder 1 and a lower holder which correspond to an upper turret and alower turret in a turret punch press and a ram (striker) 5 which canmove freely in the vertical direction and adjust its vertical position.Since this type of punch press is publicly known, detailed descriptionof whole configuration of the punch press is omitted.

To the upper holder 1 is attached a rotating mold indexing device 7 forperforming indexing of orientation of an upper mold (not shown) whichadds a process with orientation, for example a long hole, to aplate-like work W. The rotating mold indexing device 7 has a cylindricalrotating sleeve 11 rotatably supported by the upper holder through aplurality of bearings 9 and an annular worm wheel 13 is fixed integrallywith an upper part of the rotating sleeve 11.

The worm wheel 13 is engaged with a worm gear (not shown) rotated by areciprocally-rotatable control motor M. A dog 17 for activating anorigin sensor 15 such as a limit switch provided at an appropriateposition of the upper holder 1 is attached to the worm wheel 13.Alternatively, a timing pulley and a timing belt in place of the wormwheel and the worm gear may be used and the timing pulley may be rotatedby the control motor.

Accordingly, when the worm wheel 13 is rotated by the control motor Mand the origin sensor 15 is activated by the dog 17, it can be detectedthat the upper mold attached to the rotating sleeve 11 is located at anorigin in the rotation direction. Alternatively, the origin can bedetected by using a motor with absolute encoder without a component suchas the origin sensor. Rotational position of the upper mold from theorigin can be detected by detecting rotation of the control motor M witha rotating sensor 19 such as a rotary encoder.

A mold holder 21 is disposed above the rotating mold indexing device 7so as to be movable in the vertical direction. More specifically, guidepins 23 vertically arranged at plural places on an upper face of theupper holder 1 are supported by sliders 25 so as to be movable in thevertical direction and lifter springs 27 for urging the sliders 25upwards at all time are elastically installed between the sliders 25 andthe upper holder 1.

The plural sliders 25 are connected with each other in one unit by alifter plate 29 and a cylindrical holder sleeve 31 is attached to thelifter plate 29 at a position corresponding to the rotating sleeve 11.The holder sleeve 31 serves to detachably support the upper moldattached to the rotating mold indexing device 7, a lower end of theholder sleeve 31 is fitted into the rotating sleeve 11 from above so asto be movable in the vertical direction and an annular projecting part33 for supporting the upper mold is provided at the lower end of theholder sleeve 31.

A tapping tool 35 (tapping device) used by being attached to therotating mold indexing device 7 with the above-mentioned configurationhas a cylindrical shank body 37 fitted into the rotating sleeve 11 so asto be movable in the vertical direction. A vertical key groove 41engaging with a key 39 provided at a lower part on an inner peripheralface of the rotating sleeve 11 is formed on an outer peripheral face ofthe shank body 37.

A tap holder 45, rotation of which is controlled by a key 43 of theshank body 37 is provided in the shank body 37 so as to be movable inthe vertical direction and a tap 47 is detachably attached to a lowerpart of the tap holder 45 so as to protrude downwards. An upper part ofthe tap holder 45 protrudes into a large diameter hole 37H provided atthe shank body 37 and an elastic member 49 such as a coil spring forurging the tap holder 45 upwards at all time is elastically installedbetween a bottom part of the large diameter hole 37H and the upper endof the tap holder 45.

A vertical through hole 45H communicating to a tap attachment hole towhich the tap 47 is attached is provided at the tap holder 45 as an oilchannel. Oil flowing into the through hole 45H reaches a front end ofthe tap 47 through a vertical minute groove (not shown) formed on a holeinto which a shank of the tap 47 is inserted.

A cylindrical work brace 51 which protrudes up to a lower position thanthe front end (lower end) of the tap 47 in normal state is rotatablyattached to the lower end of the shank body 37 through a bearing. Anengaging ring 53 which can engage with the inner projecting part 33 ofthe holder sleeve 31 from above is relatively rotatably attached to anouter peripheral face of the upper end of the shank body 37 through abearing.

A downward movement transmitting means 55 for transmitting downwardmovement of the ram 5 to the tap holder 45 is provided at the upper partof the shank body 37. More specifically, a cylindrical head holder 57 isrelatively rotatably supported by the upper part of the shank body 37through a bearing and a pressing rod 59, a lower end face of which abutson an upper end face of the tap holder 45 in the normal state, isprovided in a vertical large diameter hole 57H formed in the head holder57 so as to be movable in the vertical direction. A vertical throughhole 59H communicatable with the through hole 45H of the tap holder 45is formed in the pressing rod 59 as oil channels.

In the large diameter hole 57H of the head holder 57, a piston 61 havinga vertical through hole 61H as an oil channel in its axis part above thepressing rod 59 is fitted so as to be movable in the vertical directionand as an example of an elastic means that can freely transmit downwardmovement of the piston 61 to the tap holder 45 through the pressing rod59, an elastic member 63 such as a coil spring and a rubber body iselastically installed between the piston 61 and the pressing rod 59. Thespring constant of the elastic member 63 is set to be smaller than thespring constant of the elastic member 49 urging the tap holder 45upwards and the elastic member 63 constitutes a shock absorbing meansfor absorbing shock when a front end of the tap 47 is engaged with aprepared hole of a work W.

A head member 65 that can freely press down the piston 61 is engagedwith the upper part of the large diameter hole 57H of the head holder 57so as to be movable in the vertical direction. The head member 65 iscontrolled in terms of upward movement and vertically movably supportedby a plurality of guide pins 67 vertically installed at the head holder57, and urged upwards at all time by a plate-holding elastic member 69such as a coil spring elastically installed between the head member 65and the head holder 57. A vertical large diameter hole 65H which can beconnected to an oil mist exhaust nozzle 5H provided at the ram 5 as wellas a small diameter through hole 61H provided at the piston 61 is formedin the axis part of the head member 65 as an oil mist channel.

With the above-mentioned configuration, as in general punch presses,overall operation of the punch press is performed by control of an NCdevice 71 and the control motor M of the rotating mold indexing device 7is controlled by a motor control means 73 with a rotation directionswitch means 75. That is, when a general upper mold is attached to therotating mold indexing device 7, rotation the control motor M iscontrolled intermittently to perform rotation indexing of the uppermold. When the tapping tool 35 is attached to the rotating mold indexingdevice 7, the control motor M is controlled so as to continuously rotatepositively at high-speed rotation suitable for cutting conditions of thetap 47 provided at the tapping tool 35 and rotate reversely at thetermination of tapping process.

With the above-mentioned configuration, when a general upper mold isattached to the rotating mold indexing device 7, after the rotating moldindexing device 7 is positioned relatively at a position below the ram5, according to a command from the NC device 71, the motor control means73 performs rotation control of rotating the control motor Mintermittently to position the upper mold at a desired angle.

When the tapping tool 35 is attached to the rotating mold indexingdevice 7, after the rotating mold indexing device 7 is positionedrelatively at a position below the ram 5, tapping process is carried outin a prepared hole previously formed on the work W by the tap 47provided in the tapping tool 35.

As shown in FIG. 1, the dog 17 provided at the rotating mold indexingdevice 7 activates the origin sensor 15 and the rotating sleeve 11, theworm wheel 13 and the like is located at the origin in the rotationdirection, and the ram 5 in the punch press descends to abut on the headmember 65 (the state shown in FIG. 1). After that, when the ram 5further descends, the tapping tool and the holder sleeve descend.

At this time, since the lifter spring 27 is a relatively weak spring,the holder sleeve 31 and the tapping tool 35 are lowered againstenergizing force of the lifter spring 27.

As described above, when the holder sleeve 31 and the tapping tool 35descend, the work brace 51 provided at the lower end of the shank body37 abuts on an upper face of the work W. Further, when the ram 5 descendslightly, the work brace 51 presses the work W onto a die D provided onthe lower holder 3 for fixation by energizing force of the elasticmember 69.

Therefore, tapping process can be carried out stably withouttransferring the work W during tapping process by the tap 47.

As described above, in the state where the work brace 51 presses thework W onto the die D, when descending of the ram 5 is stopped and oilmist is ejected from the high-diameter oil mist exhaust nozzle 5Hprovided at the ram 5, oil falls from the vertical through hole 61H ofthe piston 61 and however, fluid pressure between the head member 65 andthe piston 61 is gradually increased, thereby to lower the piston 61gradually. Accordingly, the piston 61 as a pressing means for pressingthe tap holder 45 downwards presses the tap holder 45 downwards againstenergizing force of the elastic member 49 through the elastic member 63and the pressing rod 59. Thus, the front end (lower end) of the tap 47provided at the lower end of the tap holder 45 is engaged with theprepared hole previously formed in the work W.

As described above, when the front end of the tap 47 is engaged with theprepared hole in the work W, the control motor M is positively rotatedat high speed under control of the motor control means 73, thereby torotate the tap 47 positively.

As the operation of engaging the tap 47 with the prepared hole of thework W, the following operation is possible in place of the operation ofejecting oil mist from the oil mist exhaust nozzle 5H of the ram 5. Thatis, in the state where the work brace 51 presses and fixes the work W asdescribed above, when the ram 5 descends, thereby to lower the headmember 65, the elastic member 63 is further compressed through thepiston 61, and the tap holder 45 is lowered against energizing force ofthe elastic member 49 by the elastic member 63 and the pressing rod 59.

Subsequently, when the front end of the tap 47 provided at the tapholder 45 is engaged with the prepared hole previously formed in thework W, descending of the ram 5 is stopped, positive rotation of thecontrol motor M is started by the motor control means 73 and the tap 47is positively rotated at high speed with the number of rotationssuitable for cutting conditions.

Whether or not the front end of the tap 47 is engaged with the preparedhole of the work W can be detected appropriately by detecting loadchange in an actuator for lowering the ram 5, detecting passage ofpreset time since descending of the ram 5, or the like. When the frontend of the tap 47 is engaged with the prepared hole of the work W, theelastic member 63 functions as a shock absorbing means for absorbingshock and prevents the tap 47 from breakage during the above-mentionedengagement.

As described above, in the state where the front end of the tap 47 isengaged with the prepared hole in the work W, when the control motor Mis positively rotated at high speed and the tap 47 is positively rotatedat a rotational speed suitable for tapping process, the tap 47 digs intothe prepared hole in the work W and is propelled to descend activelywhile performing tapping process.

At this time, oil mist ejected from the oil mist exhaust nozzle 5H ofthe ram 5 falls to the tap 47 through the through holes as oil channelsformed in the head member 65, the piston 61, the pressing rod 59 and thetap holder 45 so as to cool the tap 47 and is led by sliding parts ofthe head member 65, the piston 61, the pressing rod 59 and the tapholder 45 to serve the lubricating function. As a result, in the tap 47,life can be extended and each sliding part can be operated moresmoothly.

When the tap 47 is rotated positively and tapping process is started,the origin sensor 15 is activated by the dog 17 at each rotation of thetap 47. Thus, by counting an actuating signal of the origin sensor 15 inthe motor control means 73 and detecting rotation of the control motor Mby the rotating sensor 19 since the actuating signal of the originsensor 15 is input, the amount of ingress of the tap 47 with respect tothe prepared hole of the work W can be detected. Even with theconfiguration in which the number of rotations of the control motor Msince start of rotation of the control motor M is detected by therotating sensor 19, the number of rotations of the tap 47 can bedetected.

Further, by detecting that a predetermined time has elapsed sincepositive rotation of the control motor M is stated, the number ofrotations of the tap 47 can be roughly detected.

Accordingly, when the rotation direction switch means 75 provided in themotor control means 73 detects (determines) whether or not the controlmotor M has positively rotated a predetermined number of times orpredetermined time has elapsed since start of positive rotation and onthe basis of the determination, positive rotation of the control motor Mis stopped and rotation direction is reversed, the tap 47 retreats anddraws out from the prepared hole of the work W.

By raising and returning the ram 5 to the original position after thetap 47 draws out from the prepared hole of the work W, components suchas the holder sleeve 31, the shank body 37 and the head member 65returns to an initial state. Ejection of oil mist from the oil mistexhaust nozzle 5H of the ram 5 is stopped at stoppage of positiverotation of the tap 47 under control of the NC device 71.

As understood from the above-mentioned description, in this embodiment,since the control motor M for rotating the rotating mold indexing deviceof the punch press can freely carry out control in normal rotating moldindexing and control in tapping process by the motor control means 73,tapping process using the rotating mold indexing device can be performedeasily.

Since tapping process is started by rotating the tap 47 positively inthe state where the front end of the tap 47 is engaged with the preparedhole of the work W, the tap 47 starts to be intruded into the preparedhole of the work W concurrently with start of positive rotation of thetap 47 and therefore, control of the number of screw heads with respectto the prepared hole, that is, control of the amount of intrusion of thetap 47 with respect to the prepared hole can be easily performed.

Since the tapping tool 35 is detachable from the rotating mold indexingdevice 7, the general upper mold can be freely replaced with the tappingtool and the rotating mold indexing device 7 can be utilizedeffectively.

Further, since the motor control means 73 comprises the rotationdirection switch means 75 for stopping positive rotation of the controlmotor M and switching to reverse rotation during tapping process,tapping process with respect to the prepared hole of the work W can beperformed properly.

Next, with reference to FIG. 2, another embodiment of the tapping toolof the present invention will be described. Concerning the samecomponents as those in the tapping tool 35 described with reference toFIG. 1, 100 are added to reference numerals in FIG. 1 and the addedreference numerals are given in FIG. 2. Due to duplication, descriptionof the same configuration is not repeated and configuration based ondifference between them will be described.

In the tapping tool 35, the head holder 57 and the shank body 37 arerotatably connected with each other by the bearing 87. On the otherhand, in a tapping tool 100 shown in FIG. 2, a head holder 157 and ashank body 137 are connected and fixed by a screw part 187. Accordingly,the head holder 157 and the shank body 137 are formed and rotated in oneunit.

On the other hand, head members 165, 165 a, and 165 b are formed andfixed in one unit and engaged with a cylinder part of the head holder157 slidably in the vertical direction. Accordingly, the head members165, 165 a, and 165 b also rotate integrally with the head holder 157and the shank body 137.

Further, a non-rotating head 181 is provided at the head members 165,165 a, and 165 b via a thrust bearing 179. Here, the non-rotating head181 is rotatable with respect to the head members 165, 165 a, and 165 bby the thrust bearing 179. In other words, even when the head holder157, the shank body 137, and the head members 165, 165 a, and 165 brotate, the non-rotating head 181 remains stationary without rotatingwith the striker 5.

Like the above-mentioned tapping tool 35, a through hole 165H is formedat the non-rotating head 181 and the head member 165.

Next, as described above, although the through hole 61H is formed in thepiston 61 of the tapping tool 35, no through hole is formed in a piston161 of the tapping tool 100 of this embodiment. In this case, compressedoil mist flowing through the through hole 165H presses down the piston161 and passes through a gap between the periphery of the piston 161 andan inner wall of the head holder 157. For this reason, to facilitate theoil mist to pass through the gap, no O ring (O-shaped rubber packing)provided at the piston 61 of the tapping tool 35 is formed on theperiphery of the piston 161.

With the above-mentioned configuration, when the tapping tool 100inserted into the rotating sleeve 11 and the holder sleeve 31 shown inFIG. 1 is lowered by the striker 5 and the lower end abuts on the workW, the shank body 137, the head holder 157, and the head members 165,165 a, and 165 b rotate together through the key 39 inserted into andengaged with a key groove 141 a by the rotating sleeve 11. However, thenon-rotating head 181, a work brace 151 and an engagement ring 153remain stationary without rotating. Since vertical operation of thetapping tool 100 is same as that of the tapping tool 35, descriptionthereof is not repeated.

In the tapping tool 100 of this embodiment, when the operator insertsthe tapping tool 100 into the rotating sleeve 11 and the holder sleeve31 shown in FIG. 1, even if the operator operates holding the headholder 157, the shank body 137 does not rotate. Thus, since a key groove141 can be aligned with the key 39 when insertion, assembling operationis made more efficient.

Although a reference numeral 163 of the above-mentioned embodiment shownin FIG. 2 refers to a coil spring as in the embodiment shown in FIG. 1,the same effect can be achieved even when the coil spring is replacedwith a cylindrical pipe member.

Next, with reference to a figure, a tapping process device (tappingdevice) of the embodiment of the present invention will be described.

Referring to FIG. 3, the tapping process device of the embodiment of thepresent invention has a tapping unit 203 with a tap 201 for performingtapping process with respect to the prepared hole in the work W and atap die 205 (tapping device) for supporting the work W in opposed to thetap 201.

The tapping unit 203 has a cylindrical shank body 209 which built a tapholder 207 holding the tap 201, which is capable of moving only in thevertical direction therein, and a cylindrical work brace 211 that canfreely press the work W onto the tap die 205 is rotatably provided at afront end (lower end in FIG. 3) of the shank body 209.

The shank body 209 in the tapping unit 203 is supported by a cylindricalrotating body 215 rotatably provided at an upper holder 213 such as anupper turret in a turret punch press, for example, so as to be movablein the vertical direction and rotate integrally with the rotating body215. To rotate the rotating body 215, a rotating transmission means 217like an worm wheel is provided above the rotating body 215 and therotating transmission means 217 is engaged with a worm (not shown)rotated by a tap rotating motor (not shown in FIG. 3) comprised of aservo motor. That is, the rotating body 215 is rotated positively andreversely by a tap rotating motor.

To vertically move the shank body 209 and the tap 201 with respect tothe rotating body 215, a tap transferring actuator (not shown in FIG. 3)is provided. In the case where the tapping unit 203 is attached to thepunch press, for example, the tap transferring actuator corresponds toan oil hydraulic cylinder, for example, for vertically transferring aram (striker) 219 in the punch press.

With the above-mentioned configuration, when the rotating body 215 isrotated by the tap rotating motor and the tap transferring actuator isactuated, thereby to transfer the shank body 209 toward the tap die 205(downward direction in FIG. 3), the tap 201 installed at the shank body209 rotates integrally with the rotating body 215 and the shank body 209and moves together in the same direction.

When the work brace 211 provided at the front end of the shank body 209presses the work W onto the tap die 205, thereby to stop movement of theshank body 209, the tap 201 moves with respect to the shank body 209 andthe front end of the tap 201 intrudes into the prepared hole of the workto perform tapping process of the prepared hole. Since the configurationof moving the tap 201 with respect to the shank body 209 may employ apublicly-known configuration, detailed description thereof is omitted.

As described above, when the tap rotating motor is rotated reversely torotate the tap 201 reversely following tapping process of the preparedhole of the work W, the tap 201 moves so as to depart from the preparedhole of the work W and returns to an initial state by bringing back theshank body 209 to the original position.

The tap die 205 is attached to a lower holder 221 like a lower turret inthe turret punch press so as to be opposed to the tapping unit 203. Thetap die 205 has an outer cylinder 225 with a ring-like protruded worksupporting part 223 for supporting the work W so as to be opposed to thework brace 211 and an operator 227 pressed and operated by the front endof the tap 201 passing through the work W is movably provided in theouter cylinder 225.

More specifically, the operator 227 is formed like a piston fitted intothe outer cylinder 225 so as to be movable in the vertical direction andurged to the side of the work supporting part 223 at all time by anenergizing means consisting of an elastic member 231 such as a springelastically installed between a cover member 229 attached to the outercylinder 225 and the operator 227.

A projecting part 235 which can be freely fitted into a through hole 233formed in the center of the work supporting part 223 is provided on anend face of the operator 227 on the side of the work supporting part 223and a cylindrical part 237 slidably passing through the cover member 229is provided on an end face opposite to the end face on the side of thework supporting part 223. Communicating paths 241 which communicates adischarge hole 239 like a hole, a groove or the like for dischargingchips and the like generated during tapping process to the end face onthe side of the projecting part 235 are formed at plural places of theprojecting part 235.

A circumferential groove 243 that communicates with an air port 245formed in the outer sleeve 225 when being pressed and lowered by the tap201 passing through the work W is formed on a circumferential face, andcommunicated with a communicating hole 247 (air exhaust hole 247)communicating with a space 246 in which the elastic member 231 isdisposed. The space 46 communicates with the outside through a hole 229Hformed in the cover member 229.

The air port 245 is connected with a pressure source 249 and a pressuresensor 253 as an example of a sensor for detecting whether or not thecircumferential groove 243 is connected with the air port 245 isprovided at a connecting path 251 connecting the air port 245 to thepressure source 249. In the configuration in which the air port 245 ofthe outer sleeve 225 is connected with the connecting path 251, it ispreferred to provide a circumferential groove on the circumferentialface of the outer sleeve 225, corresponding to the connecting path 251.

As shown in FIG. 4, to a control device 255 for controlling the tappingprocessing device as mentioned above, the pressure sensor 253 and a taptransferring actuator 259 for vertically transferring a tap rotatingmotor 257 and the tapping unit 203 (in the case of the configuration ofvertically transferring the tapping unit by using the ram of the punchpress, it corresponds to an actuator for vertically transferring theram) are connected.

The control device 255 has a tap breakage determining means 261 fordetermining breakage of the tap 201 and a sensor state monitoring means263 for monitoring the state of the pressure sensor 253 on the basis ofan input signal sent from the pressure sensor 253.

With the above-mentioned configuration, when the tap rotating motor 257is rotated positively, thereby to rotate the tap 201 positively and thetap transferring actuator 259 is activated, thereby to start transfer ofthe tapping unit 203 toward the tap holder 207 (start of tappingprocess) under control of the control device 255 (step S201), the sensorstate monitoring means 263 monitors the state of the pressure sensor 253(step S202).

In an initial state where tapping process is started, the operator 227is pressed up by operation of the elastic member 231, thecircumferential groove 243 of the operator 227 is not connected with theair port 245 provided at the outer sleeve 225, pressure within theconnecting path 251 maintains to be high and the pressure sensor 253remains in the ON state. Therefore, when the pressure sensor 253 is inthe OFF state in the initial state, failure of the pressure sensor 253can be detected (step S203).

Further, by monitoring the pressure sensor 253, failure of an airfeeding system, for example, can be detected. Failure on whether or notthe operator 227 in the tip die 205 returns to the normal position canbe also detected. Therefore, since improper state of the pressure sensor253, the air feeding system or the tip die 205 can be found bymonitoring the state of the pressure sensor 253 in the step 3, troubleduring process can be prevented from occurring.

As mentioned above, when the tap 201 is rotated positively to starttapping process, as mentioned above, the work brace 211 presses andfixes the work W onto the work supporting part 223 and then tappingprocess is performed with respect to the prepared hole of the work W.The tap breakage determining means 261 determines whether or not thestate of the pressure sensor 253 changes (change of a detected value)within predetermined time since the tapping process is started (stepS204) and in the case where the detected value of the pressure sensor253 does not change within the predetermined time, detects breakage ofthe tap 201 (step S205) and makes emergency stop (step S206).

That is, when there is breakage in the tap 201, the tap 201 does notintrude into the prepared hole of the work W nor pass through the work Wto press onto the operator 227. Accordingly, the circumferential groove243 of the operator 227 is not connected with the air port 245 of theouter sleeve 225, pressure within the connecting path 251 maintains tobe high and the pressure switch 253 (pressure sensor 253) remains in theON state. Similarly, the case where the operator 227 does not operatenormally due to abnormal wear of a contact part of the tap 201 and theoperator 227 or the like can be detected.

When there is no breakage in the tap 201, the tap 201 intrudes into theprepared hole of the work W, passes through the work W to abut on theprojecting part 235 of the operator 227 and presses down the operator227 against energizing force of the elastic member 231. When theoperator 227 is pressed down and the circumferential groove 243 of theoperator 227 communicates with the air port 245 of the outer sleeve 225,air in the connecting path 251 flows into the circumferential groove 243and pressure in the connecting path 251 is decreased. Thus, the pressuresensor 253 is brought into the OFF state.

Therefore, when it is detected that the state of the pressure sensor 253has changed within the predetermined time (step S207), it is determinedas normal and operation is continued (step S208). When tapping processof the prepared hole of the work W is carried out by lowering the tap201, rotation of the tap 201 is stopped (step S209).

Subsequently, the tap rotating motor 257 is rotated reversely, therebyto rotate the tap 201 reversely (step S210). In the state where the tap201 starts to be rotated reversely, it is determined whether or not thepressure sensor 253 is in the OFF state (step S211) and if not, failureof the pressure sensor is detected (step S212). Similarly, faultybehavior that the operator 227 does not return to the original positioncan be detected.

It is determined whether or not the state of the pressure sensor 253 haschanged within the predetermined time since start of reverse rotation ofthe tap 201 (step S213) and when there is no change, breakage of the tap201 is detected (step S214) and emergency stop is performed (step 15).That is, in the case where breakage occurs when the tap 201 is pulledout from the work W, the front end of the tap 201 abuts on theprojecting part 235 of the operator 227, the elastic member 231 preventsthe operator 227 from ascending and the circumferential groove 243 ofthe operator 227 and the air port 245 of the outer sleeve 225 are keptto be connected with each other. Accordingly, the pressure sensor 253remains in the OFF state and breakage of the tap 201 can be detected.Similarly, faulty behavior that the operator 227 does not return to theoriginal position can be detected.

In the case where there is no breakage in the tap 201, when the tap 201ascends, the operator 227 is moved up by action of the elastic member231, connection of the circumferential groove 243 of the operator 227and the air port 245 of the outer sleeve 225 is cut, pressure in thecommunicating path (connection path) 251 is increased and the pressuresensor 253 is brought into the ON state.

Therefore, when it is detected that the pressure sensor 253 is broughtinto the ON state (step S216), it is determined as normal and operationis continued (step S217) and then reverse rotation of the tap 201 isstopped (step S218), thereby to return to the initial state.

As understood, since the sensor state monitoring means 263 monitors thestate of the pressure sensor 253 when the pressure sensor 253 changesfrom the ON state to the OFF state, failure of the sensor, if occurs,can be detected.

The communicating hole 247 provided at the operator 227 is communicatedwith space in which the elastic member 231 is installed in theabove-mentioned configuration, and as shown by imaginary lines in FIG.3, it is preferred that the communicating hole 247 is communicatedtoward the lower part of the discharge hole 239 of the cylindrical part237.

As described above, by forming the communicating hole 247 so as to beinclined toward the lower part of the discharge hole 239 of thecylindrical part 237, when the operator 227 is lowered by being pressedby the front end of the tap 201 and the circumferential groove 243 iscommunicated with the air port 245, air is ejected from thecommunicating hole 247 toward the lower part of the discharge hole 239.Accordingly, negative pressure occurs in the lower part of the dischargehole 239 and outside air is sucked from the communicating path 241provided at the projecting part 235. Thus, chips generated duringtapping process by using the tap 201 are sucked from the communicatingpath 241 and then discharged through the discharge hole 239.

As understood, the discharge hole 239 of the cylindrical part 237functions as discharging chips and the like and the communicating hole247 constitutes an air exhaust hole for ejecting air toward the lowerpart of the discharge hole 239. Since air ejecting from the air exhausthole into the discharge hole 239 serves to suck outside air from thecommunicating path 241, discharge of chips generated during tappingprocess can be performed effectively.

Next, with reference to FIGS. 7 to 10, another embodiment of the tap dieof the present invention will be described. Concerning the samecomponents as those in the tap die 5 described with reference to FIG. 3,300 are added to reference numerals in FIG. 3 and the added referencenumerals are given in FIGS. 7 to 10. Due to duplication, description ofthe same configuration is not repeated and configuration based ondifference between them will be described.

In the tap die 5, when the operator 27 is lowered, space is generatedbetween the lower face (back face) of the work supporting part 23 of theouter sleeve 25 and the upper face of the operator 27. However, since nocompressed air flows into this space, there may be cases where offcuts(scraps) generated during tapping process enter into the space and theoperator cannot completely ascend and return to the original position.For this reason, this embodiment intends to provide the configuration inwhich compressed air can flow into the space. Referring the figures, theimproved configuration of the present invention will be described below.

As shown in FIGS. 7 to 10, an annular groove 343 is formed at an upperpart of the inner circumference of an outer sleeve 325 of a tap die 300in this embodiment. An air port 345 is formed so as to pass through theouter sleeve 325 in the horizontal direction and a vertically-extendedvertical groove 371 which connects the groove 343 to the air port 345 isformed.

Like the tap die 5, an operator 327 which can freely slide in thevertical direction is provided in the outer sleeve 325. Therefore, whenthe tap 1 descends, thereby to press the operator 327 downwards, spaceis generated between an inner wall part of the outer sleeve 325 (a wallface corresponding to the lower face (back face) of the work supportingpart 23 shown in FIG. 3) and the upper face of the operator 327. Airflows into the space through the air port 345, the vertical groove 371and the groove 343.

On the other hand, as shown in FIG. 10, a bar-like dog 381 is engagedwith the operator 327. The dog 381 is engaged so as to run across acylindrical wall of the operator 327. Accordingly, air can be passedthrough the space located on both sides of the dog 381, that is, thespace other than the dog 381 and the cylindrical wall of the operator327, in the vertical direction. A tap receiver 381 a protruding upwardsis formed at the center of the dog 381.

With the above-mentioned configuration, when the tap 1 descends andabuts on the tap receiver 381 a, the operator 327 is pressed downdownwards. Thus, space is generated between the inner wall part of theouter sleeve 325 (the wall face corresponding to the lower face (backface) of the work supporting part 23 shown in FIG. 3) and the upper faceof the operator 327. Air flows into the space through the air port 345,the vertical groove 371 and the groove 343. Since the air flows into thespace, the offcuts (scraps) accumulated on upper faces of the operator327 moved downwards and the dog 381 are blew away and the upper faces ofthe operator 327 and the dog 381 become clean. For this reason, when thetap 1 completes descending and ascends, the upper face of the operator327 adheres closely to the inner wall part of the outer sleeve 325 andcan ascend and return to the original position.

As shown in FIG. 7 and FIG. 8, the outer sleeve 325 extends downwards. Aplurality of through holes 375 for taking air thereinto are formed atappropriate places of the sleeve extending downwards. The through holes375 are formed so as to be inclined downwards as they proceed to theinner side. The plural through holes 375 are communicated with eachother through a circumferential groove 377.

Air formed in the lower holder 221 (FIG. 3) is compressed in a channel379, the compressed air flows into all of the plural through holesthrough the circumferential groove 377, and the air further flows into alower space 387 of the outer sleeve 325.

Since air flows into the lower space 387 and the air is ejecteddownwards, periphery of an upper space 385 of the outer sleeve 325 isbrought into the state under negative pressure close to vacuum. Due tothe state under negative pressure, the offcuts (scraps) accumulated onupper faces of the operator 327 and the dog 381 and blew away are suckeddownwards, thereby to improve the effect of removing the offcuts(scraps).

Entire contents of Japanese Patent Application No. 2002-312811 (filed onOct. 28, 2002) and Japanese Patent Application No. 2003-039705 (filed onFeb. 18, 2003) are incorporated into the description by reference.

The present invention is not limited to the above-mentioned embodimentsand can be executed in the other mode with appropriate modifications.

1. A tapping device, comprising: a tap holder, provided in a verticallymovable shank body which can be freely attached to a rotating moldindexing device rotatably provided at a punch press, the tap holderhaving a tap at a lower end and being provided so as to be movable in avertical direction and urged upwards; a downward movement transmitterwhich receives and transmits a downward motion of a ram provided at thepunch press so as to be movable in the vertical direction to the tapholder, the downward movement transmitter being at an upper part of theshank body, and the downward motion of the ram, which is received by thedownward movement transmitter, is transmitted to the upper part of theshank body; and an elastic member positioned within a space provided inthe shank body, the elastic member extending between a bottom of thespace and an upper end of the tap holder so as to urge the tap holderupwards.
 2. A tapping device according to claim 1, wherein a workpiecebrace is rotatably provided at a lower end of the shank body.
 3. Atapping device according to claim 2, wherein an oil channel for guidingoil supplied from the ram to the tap is provided in the downwardmovement transmitter and the tap holder.
 4. A tapping device,comprising: a tap holder provided in a vertically movable shank bodywhich can be freely attached to a rotating mold indexing devicerotatably provided at a punch press, the tap holder having a tap at alower end and being provided so as to be movable in a vertical directionand urged upwards; a downward movement transmitter which receives andtransmits a downward motion of a ram provided at the punch press so asto be movable in the vertical direction to the tap holder, wherein thedownward motion of the ram, which is received by the downward movementtransmitter, is transmitted to the upper part of the shank body and,wherein the downward movement transmitter has a pressing device whichpresses the tap holder downwards by fluid pressure supplied from the ramand a shock absorber; and an elastic member positioned within a spaceprovided in the shank body, the elastic member extending between abottom of the space and an upper end of the tap holder so as to urge thetap holder upwards.
 5. A tapping device according to claim 4, wherein aworkpiece brace is rotatably provided at a lower end of the shank body.6. A tapping device according to claim 5, wherein an oil channel forguiding oil supplied from the ram to the tap is provided in the downwardmovement transmitter and the tap holder.